Cutting implements, such as utility knives of the type in which the cutting blade is removable from the handle are well known, the combination of knife blade and handle being typically referred to as a utility knife. Such utility knives are normally available both with retractable blades, such as the type described in U.S. Pat. No. 3,192,624, and with non-retractable blades. Generally, such prior art utility knives comprise the type where two separate complimentary halves are secured together by a screw, such as the type of utility knife manufactured by Stanley Model No. 299, or the type disclosed in U.S. Pat. Nos. 2,376,887; 2,862,296; 2,948,961; 3,062,147; 3,107,426; or 3,192,624. Other prior art utility knives of the non-retractable type have been utilized which have a separate carrier member which pivots into and out of a handle, such as the type disclosed in U.S. Pat. No. 2,245,096. Some of the previously mentioned types of utility knives in which two separable halves are utilized provides for storage of replacement blades within the handle housing but often lack a means for securing these blades within the housing and they rattle around in the knife during storage and often get dull before these blades have had an opportunity to be utilized.
In addition, some such prior art knives are formed of metal die cast housings with a screw to hold the handle together. While the hard die cast housings serve to make the utility knife a durable work tool, the hard surface can be uncomfortable or otherwise ergonomically undesirable leading to blisters. Maintaining a good grip is also a problem with such knives. Additional problems with such knives relates to the use of the attachment screw. Generally, since the screw is centrally located to clamp the blade, a stripped thread will have a tendency to separate the halves and become a hazard. Moreover, since they require use of a screwdriver to remove the halves, the screw makes replacing the blades more difficult and potentially less safe if one slips.
Plastic injection molded utility knives have attempted to address the comfort issue by a dual molding process that combines a rigid plastic housing, typically of polypropylene, with a softer outer cover externally molded thereto, typically made from an elastomeric material such as Santoprene. The surface areas of the two materials chemically adhere due to the nature of the materials. However, these devices lack the safety, durability and feel of the heavier die cast variation as they wear quickly and the sharp blade tends to cut through. Moreover, simply molding an elastomeric material to the exterior of a metallic housing is not possible since such elastomeric material does not bond or adhere to metallic surfaces as it does with compatible plastic surfaces.
Furthermore, in several of these prior art utility knives having separate halves, the portion of the cutting blade that remains in the housing has a tendency to bear against the metal of the housing when pressure is applied to the cutting edge. This typically results in the unused edge becoming dull prior to actual use of the blade.
Accordingly, it is an objective of the invention to provide a non-retractable hardened utility knife with a soft, grippable and securely fixed outer cover.
It is an additional objective of the invention to provide such a knife with a quick and easy means for accessing the blade storage compartment or changing the blade.
It is a further objective to provide such a knife with a construction that protects the internal edge of the cutting blade from being dulled from movement when the external edge of the cutting blade is in use.
It is a still further objective to provide such a device with a frontal bridge near the cutting blade to prevent the housing halves from separation during use and causing injury.
It is another objective to provide such a knife with an economical and efficient method of manufacture.
Additional objectives will be apparent from a review of the preferred embodiment of the invention described herein.